Joystick type control device with displacement feel

ABSTRACT

The stick of a joystick type control device is rigidly affixed to a carrier plate that extends normal to it. The plate is gimbal mounted on a fixed base and has four reaction receiving elements equidistant from the stick axis, arranged two along each gimbal axis, at opposite sides of the stick. Four springs react, all in the same direction, between the fixed base and the plate, one against each reaction receiving element. When the stick is in a normal position the springs exert equal forces.

United States Patent 1 Karlsson et a1.

[ JOYSTICK TYPE CONTROL DEVICE WITH DISPLACEMENT FEEL [75] Inventors: Ake Gustav-Adolph Karlsson; Bengt Furchtegott Staffan Svenning, both of Linkoping, Sweden [73] Assignee: Saab-Scania Aktiebolag, Linkoping,

Sweden 221 Filed: May 23,1972

21 Appl. No.: 256,012

[52] US. Cl. 74/471 XY [51] Int. Cl G05g 9/04 [58] Field of Search 74/471 XY, 471

{56] References Cited UNITED STATES PATENTS 2,539,217 1/1951 Willoughby 74/471 XY X 3,308,675 3/1967 Jonsson 74/471 XY [111 3,744,335 1 July 10, 1973 FOREIGN PATENTS OR APPLICATIONS 518,874 3/1955 Italy 74/471 XY Primary Examiner-Milton Kaufman Attorney-Ira Milton Jones [57] ABSTRACT The stick of a joystick type control device is rigidly affixed to a carrier plate that extends normal to it. The plate is gimbal mounted on a fixed base and has four reaction receiving elements equidistant from the stick axis, arranged two along each gimbal axis, at opposite sides of the stick. Four springs react, all in the same direction, between the fixed base and the plate, one against each reaction receiving element. When the stick is in a normal position the springs exert equal forces.

3 Claims, 5 Drawing Figures Patented July 10, 1973 3,744,335

3 Sheets-Sheet 1 Patented M 10, 1973 3,744,335

3 Sheets-Sheet 2 FIG.

Patented July 1.0, 1973 3 Sheets-Sheet 5 FIGJ.

FIG.3

FIG. 5 p

JOYSTICK TYPE CONTROL DEVICE WITH DISPLACEMENT FEEL This invention relates to joystick type controls for cranes and similar machines, and is more specifically concerned with a swingable lever control device by which two variable inputs to a machine to be controlled can be simultaneously but independently regulated, and wherein the swingable lever is biased to a normal position in such a manner that a person manipulating it can readily detect, by feel, the amount and direction of its displacement about each of a pair of axes around which it can swing.

The joystick type of control is perhaps best known in its application to airplanes, in which it had its earliest extensive use for effecting simultaneous but independent control of elevators and ailerons; but because of the natural and self-explanatory action that it has, it is coming into increasing use for control of other machines. Thus a joystick or swinging lever control may be provided for the operator of a crane, so that he can regulate lifting and lowering by moving the stick foreand-aft and can control lateral swinging of the crane boom by moving the stick from side to side.

In an airplane a joystick gives the pilot definite information about its position and effect solely by feel, inasmuch as air loads on the ailerons and elevators feed back forces that yieldingly resist motion of the stick out of a neutral position, and the magnitude of the force component in each direction corresponds, generally speaking, to the amount of displacement of the stick inthat direction. However, where a joystick type of control lever is connected with variable input producing means such as a rheostat or a hydraulic control valve, there is no such inherent feedback to the control lever, and either the stick must be urged to a normal or neutral position by some sort of biasing means not in a feedback loop, or the operator of the machine must visually determine the position of the stick from time to time. Visual determination of stick position is particularly unsatisfactory in the case of a machine such as a crane, where the operator must constantly keep his eyes on a zone remote from his station in the interests of safe and efficient operation.

Heretofore the swinging levers of joystick type controls for cranes and similar machines have not had a satisfactory feel from which an operator could detect the exact amount of displacement of the lever about each of its axes. Operators of such machines therefore required long periods of training and experience before they could operate them skillfully, and not all persons were able to achieve a high degree of skill in their operation.

In one attempt to overcome this deficiency in prior joystick type control devices, track-like guide members that embraced the lever and were formed as brackets were mounted to swing about the axes around which the lever was swingable. At least in certain embodiments, this prior expedient had the disadvantage that the lever could not be displaced from its normal position simultaneously about both of its axes of swinging motion, so that all operations of the machine had to be' performed sequentially, with aninevitable loss of efficiency and some compromise with safety. Another serious disadvantage of all such prior guide track arrangements was that both the lever and the tracks would wear down with continued use, with the result that the accuracy of the control system gradually decreased.

By contrast with these prior expedients, the present invention has for its general object the provision of a joysticktype of control device that provides a definite feel from which a person manipulating the lever of the device can know, without looking at it, the exact amount and direction of displacement of the lever from its normal position about each of its axes of swinging motion, and by which those axes are effectively defined for him.

It will be apparent that it is also an object of this invention to provide a control input device comprising a single manually manipulatable control member by which two variable inputs to a machine to be controlled can be simultaneously but independently governed, which device operates in a natural and self-explanatory manner and has a feel such that an untrained person can quickly acquire a high degree of skill in using it to control the machine on which it is installed.

It is also an object of this invention to provide a control device of the character described which has no rails, guides or similar parts that tend to wear with use, and which is simple, inexpensive and easily maintained.

With these observations and objectives in mind, the manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying drawings, which exemplify the invention, it being understood that changes may be made in the specific apparatus disclosed herein without departing from the essentials of the invention set forth in the appended claims.

The accompanying drawings illustrate one complete example of an embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIG. 1 is a perspective view of a control device embodying the principles of this invention;

FIG. 2 is a sectional view taken on the plane of the line IIII in FIG. 1;

FIG. 3 is a more or less diagrammatic view showing the control lever or stick of the device of this invention displaced from its normal position about only one of its two axes of swinging motion and illustrating the force that is required to effect such displacement of it;

FIG. 4 is a view similar to FIG. 3, but illustrating the control lever displaced about both of its axes from its normal position; and

FIG. 5 is a diagram illustrating the relationship between the force which is required to displace the control lever and the direction in which the lever is swung.

Referring now to the accompanying drawings, the numeral 1 designates a joystick type control device embodying the principles of this invention, having a lever or stick 2 which is adapted to maintain a normal position, in which it is illustrated in FIG. 1, and which can be manually swung away from that normal position in any direction in accordance with requirements for governing a machine that the device controls. The lever 2 is rigidly secured to the center of a plate-like carrier 3 which has its top and bottom surfaces normal to the axis of the lever.

The carrier 3, as hereinafter explained, is swingablyshaped frame 8 are secured to and project up from opposite marginal portions of the bottom plate 23, and the web portion 14 of the frame is parallel to and spaced above the bottom plate. The carrier 3 is disposed between the upright legs of the frame 8, and between the bottom plate 23 and the web portion 14 of the frame.

To provide for swinging motion of the carrier, and hence of the lever 2, the carrier has a gimbal connection with the base, comprising a ring 4 which surrounds the carrier with some clearance, a coaxial pair of pivotal connections 9 and 10 by which the ring is swingably supported on the base, and another coaxial pair of pivotal connections 5 and 6 by which the carrier is swingably supported on the ring. Both the carrier 3 and the ring 4 are here shown as square, but they could as well be circular, or of any other suitable shape.

The pivotal connections 9 and 10 between the ring and the base extend through the legs 12 and 13 of the inverted U-shaped frame member 8, substantially at the centers of those legs, and the pivot axis 11 that they define extends parallel to the bottom plate 23. The pivot connections 5 and 6, between the carrier 3 and the ring 4, define an axis 7 that is normal to and intersects the pivot axis 11. Both axes 7 and 11 intersect the axis of the lever 2 and are normal to it.

The lever 2 projects up from the carrier 3 through a hole in the web portion 14 of the U-shaped frame 8. The diameter of the hole 15 is of course substantially larger than that of the lever, and that hole defines the limits of swinging motion of the lever and thus of the carrier about the two coordinate axes 7 and 11 of the gimbal connection. In its normal position, illustrated in FIGS. 1 and 2, the lever is vertical and is centered in the hole 15.

To keep dirt and other articles from falling through the hole 15, a bellows-like cover 16 is secured to the stick and to the upper surface of the web 14 all around the hole.

Any movement of the lever or stick 2 must of course result in change of a variable input to a machine to be controlled. To that end, the pivot connection 10 comprises a pin 17 which is fixed to the ring 4 for rotation therewith and which extends through the leg 12 of the U-shaped frame. Secured to the outer end of that pin is the movable element 18 of an input control device 19 that has its fixed portion 20 secured to the base of the device. While the control device 19 could be a valve or the like, it is here illustrated as a potentiometer having a slider as its movable element 18 and having its stationary element connected by means of conductors 21, 22 to an associated control device (not shown), which can comprise, for example, an electro-hydraulic transformer. It will be understood that the pivotal connection 6 between the ring 4 and the carrier 3 is generally similar to that just described and that it provides for actuation of another similar control input device that has its movable element constrained to motion with the carrier 3 and has its stationary element fixed to the ring 4. Thus, rocking of the lever 2 about the axis 11 effects variation of one input to a machine to be controlled, while rocking of that lever about the axis 7 effects variation of another such input, and the two inputs can be controlled simultaneously but independently.

Reacting between the carrier 3 and the base of the device is a group of four biasing members, each comprising a compression spring 36 and a rod 29. These cooperate to urge the lever 2 towards its normal position in such a manner that a person manipulating the lever is informed by feel of the amount by which he has displaced it about each axis from its normal position. The compression springs 36 are accommodated in a hous' ing 24 which is secured to the underside of the bottom plate 23 and in which there is a block having four upright bores 25, one for each spring. Assuming that the lever 2 is in its normal position, normal to the bottom plate 23, the axes of the bores 25 are all parallel to and equidistant from the axis of the lever, and each of said bore axes intersects one of the swinging axes 7 or 11. Thus the bores 25 can be regarded as arranged in pairs, with each pair of bores disposed along one of the axes 7 or 11 and with the bores of each pair spaced to opposite sides of the lever axis.

Each of the compression springs 36 is confined in one of the bores 25, and the bore thus defines the location of the spring and the direction in which its biasing force is exerted. There are four holes 30 in the bottom plate 23, each concentric with one of the bores 25 and each somewhat smaller in diameter than its bore, and through these holes 30 extend the rods 29 that connect the springs 36 with the carrier 3 to impose the biasing forces of the springs upon the carrier.

At its underside the carrier 3 has four generally conical wells or sockets 31, in each of which the upper end portion of one of the rods 29 is engageable. These wells or sockets thus comprise reaction receiving elements on the carrier. With the lever 2 in its normal position, these wells or sockets are centered on the axes of the bores 25, and their bottoms are concavely rounded to fit the generally hemispherical upper end portions of the rods 29.

Each of the rods 29 extends a substantial distance down into its bore 25, and its lower end portion is threaded to accommodate a correspondingly threaded stop nut 33 and jam nut 34. The body portion of the stop nut 33 has a diameter to be guidingly received within the upper coils of its spring 36, and it has a cir-' cumferential flange 32 around its top that seats on the top coil of its spring. The jam nut 34 is of course tightened against the underside of the stop nut 33 to prevent undesired rotation of the latter.

The four springs 36 all have the same load response characteristics, and the stop nuts 33 are so adjusted alongthe rods 29 that with the lever 2 in its normal position all four springs exert equal upward forces P upon the carrier 3 through the rods. To provide for such adjustment-of the stop nuts, each of the rods 29 has a screw driver cross-slot across its bottom end, accessible through a hole 37 in the bottom wall 35 of the housing 24, and each stop nut has a radially opening hole 320 in its flange portion, accessible through a hole 38 in the side wall of the housing.

it will be apparent that when the stop nuts 33 are properly adjusted, the springs 36 tend to maintain the lever in its normal position, inasmuch as the equal biasing forces then exerted by the springs, which are all imposed upon the carrier in the same direction, are in balance with one another about the axes 7 and 11. It will also be apparent that when the carrier 3 is tilted, due to rocking of the lever 2, the very small lateral motion component of the upper end portions of the rods 29 is accommodated by a very slight swinging or tilting of the rods, made possible by flexing of the springs 36 and accommodated by the connections between the rods and the wells 31 in the carrier.

When the lever is rocked, a force P must be applied to it to overcome the biasing force of'one or more of the springs. If the lever is moved in one of the vertical planes 27 or 28 that lie on the respective axes 7 and 11, so that it is swung only about the other axis 11 or 7, only one of the springs 36 is compressed. However, if the lever is moved in any other direction, two springs are compressed, and a larger force P is required to effect such displacement of the lever. The variation of displacing force required to effect displacement of the lever in any particular direction is diagrammatically illustrated in FIG. 5. If the force required to move the lever in one of the planes 27 or 28 is taken as unity, then the force required to swing it to an angle of 45 relative to those planes will be equal to 2 or 1.414. This force relationship identifies the axes 7 and 11 to the operator and enables him to detect by feel any departure from swinging motion of the lever solely about one of those axes.

From the foregoing description taken with the accompanying drawings it will be apparent that this invention provides a joystick type control device by which an operator can simultaneously but independently regulate two variable inputs to a machine to be controlled and which enables him to readily determine solely by feel the amount of each input that he is commanding by his manipulation of the lever or stick of the control device.

Those skilled in the art will appreciate that the invention can be embodied in forms other than as herein disclosed for purposes of illustration.

The invention is defined by the following claims:

1. In a control device comprising a lever that is manually swingable from a defined normal position about either or both of two fixed axes that are perpendicular to one another and the lever, and by manipulation of which [ever an operator can simultaneously but independently regulate two variable inputs to a machine to be controlled, said control device further comprising means for regulating one of said inputs in correspondence with displacement of the lever from its nonnal position about one of said axes and means for regulating the other of said inputs in correspondence with displacement of the lever from its normal position about the other of said axes,

means by which the lever is supported for its swinging motion, is biased towards its normal position, and

is provided with a feel that enables a person manipulating it to detect the amount and direction of its displacement from its normal position about each of said axes, the last mentioned means comprising:

A. carrier means rigidly secured to the lever;

B. a fixed base;

C. gimbal means connected between the fixed base and the carrier means to support the latter for swinging motion, said gimbal means having pivot means that respectively define said two axes;

D. four reaction receiving surfaces on the carrier means disposed in a plane normal to the lever and equispaced from the lever, said surfaces being located to opposite sides of the lever along each of said axes; and

E. four biasing members, one for each of said reaction receiving surfaces on the carrier means, each reacting between the fixed base and its surfaces, said biasing members all having like biasing characteristics and exerting equal biasing forces upon the carrier means when the lever is in its normal position, and all exerting their biasing forces in one direction normal to said plane.

2. The control device of claim 1, further characterized by:

A. each of said reaction receiving surfaces on the carrier means defining a concave socket that opens toward the base; B. said base having four wells therein, each opening toward the carrier means and located to have its axis concentric with one of said sockets when the lever is in its normal position; and C. each of said biasing members comprising 1. a compression spring confined in one of said wells in the base, and

2. a rigid thrust transmitting member having one end engaged in one of said sockets and having its other end engaging the end of its spring that is proximal to the carrier means so as to transmit biasing forces between the spring and the carrier means.

3. A control device comprising a lever that is manually swingable to and from a defined normal position about either or both of two fixed axes that are perpendicular to one another and the lever, and by manipulation of which lever an operator can simultaneously but independently regulate two variable inputs to a machine to be controlled, said control device comprising:

A. means providing a fixed base;

B. a gimbal ring;

C. pivot means connected between the base and the gimbal ring to mount the gimbal ring for swiveling motion relative to the base about one of said axes;

D. a carrier to which the lever is rigidly secured and which has surface portions disposed generally in a plane normal to the lever;

E. other pivot means connected between the gimbal ring and the carrier to mount the latter for swiveling motion relative to the gimbal ring about the other of said axes as well as for swiveling with the gimbal ring about said one axis;

F. first variable output means connected between the base and the gimbal ring for producing a first output that depends upon the angular position of the gimbal ring relative to the base;

G. second variable output means connected between the carrier and the gimbal ring for producing a second output that depends upon the angular position of the carrier relative to the gimbal ring;

H. said surface portions on the carrier, comprising two pairs of reaction receiving surfaces, one pair for each axis, the pair of surfaces for each axis being centered therealong at opposite sides of the lever and equidistant therefrom and both being on the same surface portion of the carrier;

1. two pairs of biasing members, one of said biasing members being connected with each of said reaction receiving surfaces and each comprising a spring which also reacts against the base, the biasing members of each pair having substantially identical biasing characteristics and both imposing upon the carrier forces which are in the same direction generally parallel to the lever and which are in balance when the lever is in its normal position. 

1. In a control device comprising a lever that is manually swingable from a defined normal position about either or both of two fixed axes that are perpendicular to one another and the lever, and by manipulation of which lever an operator can simultaneously but independently regulate two variable inputs to a machine to be controlled, said control device further comprising means for regulating one of said inputs in correspondence with displacement of the lever from its normal position about one of said axes and means for regulating the other of said inputs in correspondence with displacement of the lever from its normal position about the other of said axes, means by which the lever is supported for its swinging motion, is biased towards its normal position, and is provided with a feel that enables a person manipulating it to detect the amount and direction of its displacement from its normal position about each of said axes, the last mentioned means comprising: A. carrier means rigidly secured to the lever; B. a fixed base; C. gimbal means connected between the fixed base and the carrier means to support the latter for swinging motion, said gimbal means having pivot means that respectively define said two axes; D. four reaction receiving surfaces on the carrier means disposed in a plane normal to the lever and equispaced from the lever, said surfaces being located to opposite sides of the lever along each of said axes; and E. four biasing members, one for each of said reaction receiving surfaces on the carrier means, each reacting between the fixed base and its surfaces, said biasing members all having like biasing characteristics and exerting equal biasing forces upon the carrier means when the lever is in its normal position, and all exerting their biasing forces in one direction normal to said plane.
 2. The control device of claim 1, further characterized by: A. each of said reaction receiving surfaces on the carrier means defining a concave socket that opens toward the base; B. said base having four wells therein, each opening toward the carrier means and located to have its axis concentric with one of said sockets when the lever is in its normal position; and C. each of said biasing members comprising
 2. a rigid thrust transmitting member having one end engaged in one of said sockets and having its other end engaging the end of its spring that is proximal to the carrier means so as to transmit biasing forces between the spring and the carrier means.
 3. A control device comprising a lever that is manually swingable to and from a defined normal position about either or both of two fixed axes that are perpendicular to one another and the lever, and by manipulation of which lever an operator can simultaneously but independently regulate two variable inputs to a machine to be controlled, said control device comprising: A. means providing a fixed base; B. a gimbal ring; C. pivot means connected between the base and the gimbal ring to mount the gimbal ring for swiveling motion relative to the base about one of said axes; D. a carrier to which the lever is rigidly secured and which has surface portions disposed generally in a plane normal to the lever; E. other pivot means connected between the gimbal ring anD the carrier to mount the latter for swiveling motion relative to the gimbal ring about the other of said axes as well as for swiveling with the gimbal ring about said one axis; F. first variable output means connected between the base and the gimbal ring for producing a first output that depends upon the angular position of the gimbal ring relative to the base; G. second variable output means connected between the carrier and the gimbal ring for producing a second output that depends upon the angular position of the carrier relative to the gimbal ring; H. said surface portions on the carrier, comprising two pairs of reaction receiving surfaces, one pair for each axis, the pair of surfaces for each axis being centered therealong at opposite sides of the lever and equidistant therefrom and both being on the same surface portion of the carrier; I. two pairs of biasing members, one of said biasing members being connected with each of said reaction receiving surfaces and each comprising a spring which also reacts against the base, the biasing members of each pair having substantially identical biasing characteristics and both imposing upon the carrier forces which are in the same direction generally parallel to the lever and which are in balance when the lever is in its normal position. 